Drying kiln



Patented Feb. 27, 1923.

DRYING KILN.

Appiicationfmea-fsmne 7, 1922.' semi No. 566,477.

To all whom'z't 'may concer/n,

Be itknown that I, ALEXANDER R; DUrr, of the city, oft Toro-nto, in theY county of York, Province of Ontario, Canada,-a subject of the King of Greatv Britain, have invented certain new 1 and usefiil Improvements in Drying Kilnsfof which the followingis specification.'

This invention relates to lrilns particularly adapted for vdryingI` and seasoning lumbenend my-object is to devise a 1Kiln which will dry every piece 'of lumber in a batch undergoing treatment uniformly and simultaneously, and; in I which perfect control of therate of drying is obtained;

l attain my object-bysoconstructing'the kilnv Vand arrangingthelumber therein that a positively directed circulation' of air, properly conditioned-as to moisture content and temperature, is effected through the spaces formed in the lumberpile, means being provided for a' controlled escape of moisture laden air andl the introduction of outside airfto takev its place. The invention-iis' hereinaftermore fully described and is illustrated in the accompanying drawings in Which- 1 Fig.` l is A across section of the kiln'- con-- structed in accordance 'Withmy invention;

Fig. 2V isla longitudinalL section of part ofthe-same; and

Fig. 3 isahorizental'section on the line a-ainF-ig.' 2.

In thefdrawings likenumerals of reference indicate correspondingrparts in the different-figu-resr-- -f v i v i The kiln is `constructed ofv any suitable material and inany desired manner .to form the*chamber 1, which will be provided at its ends With the usual doors. Within .the chamber ofthelziln are formed one or more lair heating-chimneys 2. These chimneys are .of oblongform and eXtendsubstanrt-iall-y the each chimney 'is open' and afplurality of openings 3 are formed in thetop, one under `each--truck. Athese yopenings being preferablyT` of -lesswvidth than the width ofthe chimney. The topi also preferably-slants upwardly from eachside towards the opening 'or openings to facilitate the passagerof higher velocity.; were maintained".A

air to theseopenings,and to bring thefopenings as close aspossibleto Athe bottoni'of thepile of lm nber1v `si ipnortefl' above f the 'Chiel-ner i as 'herein-after y described! Within each chimney is located asuitable heating coil 5, this heating coil being located above'the bottom ofthe chimney, andfpreferabl'yclose to the top. When the coils are suitably heated, air rises through the chimney and is heated in the process, constant circulationgthrough the chimney being maintained as long as the coils are heated. 'These chimneys are so' proportioned that though the' circulation caused thereby is active the air `does not move at a very high velocity. It' is preferable 4that the chimneys extend sufficiently close to the bottom of the kiln to avoid dead air space,

butnot so low' as to restrict the circulation of air under' their bottom edges.r

The effective lutil'inatio'n ofthe chimneys depend on a particular method of piling the lumber to be dried. l

To support the lumber tracks 6 are provided extending longitudinally of the kiln, on Whichtra'cks run'the Wheeled trucks 7, the vframes of these trucks ybeing of open constructionsoas not to interfere' with the free-passage of yair from` the openingsy 3. The lumber 8 is piled longitudinally ofthese trucks, .successive` layers of l lumber being separated by the narroivl transverse separators 9. The lumberis stacked With ahollowl center 10'. The heated air pfassingfrom the openingorfopenings 3 rises up into the hollow center and follows the easiest path from `the center to thefoutsideof thef'pile, whichy is' through"theinterstices of the pile laterally. Thisy'circulationv is materially improved by `making'thiefhollovv"center taper inwardly and upwardlyso that each successive layerfofY lumber'projects slightly furthe-r intothe ,hollow center than` the-llayer underneath.V This4 slight projection llhave found has a very; marked effectfin deflecting rising air laterallyy through these in- I l terstices,particularly as the velocity of the Whole' length-of the'kiln. AThe bottom Of .of `movement is therefore easily changed.

circulating air is 'not great and its direction Frornthe lovv'velo'city vof the airitalso resultsftli'at the dryingis very equable as the airwill pass as readily out through the intelsticeslofthe lower'par't of the pile of lumberns it Will'higher up, which vv fould nothe 4thecase ifa forced circulation at The preferred' construction of theopenings "in'fthe chimneyftops to `form each chimney with one continuous fopening,l and.

to use .removable lids or plates 18, which are placed over such parts of the top of each chimney as are not immediately beneath a pile of lumber, thus ensuring the passage of the air from the chimneys as far as possible taking place entirely into the heart of each lumber pile.

lit is evident that a constant circulation of air will be maintained as long as the coils are heated, and that this air will be brought into contact with the lumberrat all parts of the pile, there being no center of the pile not reached by the circulating air, as is the ease when lumber is piled in the ordinary manner and cured in kilns of the ordinary type. l

It is essential to proper drying that moisture laden air be carried away and freshoutside air be introduced to supply its place. lt is also essential that means be provided to introduce at certain stages of the erying additional moisture into the air. It is therefore of importance that the fresh air and Vthe introduced.moisture be theroughly mingled'with the circulating air before reaching the lumber. To attain these objects l jrevide the constructions l will now describe.

At each side of the kiln at intervals llprovide the outlet air ducts 11, which preferably extend upwardly to the top of the kiln and communicates by means of damper controlled openings 12 with the interior of the kiln, preferably above the lower ends of the chimneys 2. Under each chimney., and

preferably below the level of the bottom thereof, is provided a fresh air supply duct 13 provided at intervals with openings 1i in its top. Along the top of each duct run the steam pipes 15,7in which are formed perforations so placed that the steam vjets issuing from these pipes are directed into the chimney in such a way as to cross the paths of the circulating air and of the air issuing `from the openings 1li. rlhe circulating air and the fresh air are given every opportunity of picking up the moisture and the process is substantially completed, when the mingled circulating air, fresh air and steam passes through the heating coil 5. The air is thus properly conditioned before it comes Vvided with lateral openings at thpir lower ends controlled by dampers 17. At times the heat supplied by the steam from the steam spray pipes 14 may be suicient to provide as rapid a circulation as Ymay be necessary Vand at Asuch times the steam supply to the coils 5 may be @ut @i it is evident also that any other means of heating might be provided to take the place of the coils .5. i

`To ensure that none of the rising` air from thechimneys will pass out from the hollow centers of the lumber piles through the ends thereof, curtains may be hung on each end. of each pile extending from the top of the pile to the top of the chimney, though this will not usually be necessary. Y

What l claim as my invention is:

1. ln a kiln,.the combination of a closed chamber; an air heating chimney adjacent the bottoni of the kilnopen at top 4and bottom; heating coils in said chimney above the lower end thereof; means for admitting out. side air to the lower part of the chimney; andan air outlet duct communicating with the interior of the kiln.

2. ln a kiln, the combination of a closed chamber; an air heating` chimney adjacentV the bottom of the kiln open at top and bottom; heating coils'in said chimney above the lower end thereof; means for admitting outside air to the lower part of the chimney; andV an air V.outlet duct at each side ofthe Vchimney communicating with the interior ofthe kiln.V Y

3. ln a kiln, the combination of a closed chamber; an air heating chimney adjacent the bottom of the kiln open at top and bottom; heating coils in saidV chimney above the lower end thereof; means for admitting outside air to the lower part of the chimney; an air outlet duct communicating with the yinterior of the kiln; and means for injecting steam into the path of circulating air entering the lower end of the chimney and before it reaches the heating coils. Y

4. In a kiln, the combination of a closed chamber; an air heating chimney adjacent the bottom of the kilnr open at'top and bottom; heating coils in said chimney above the lower end thereof; an inlet for outside air below the lower end of the chimney; and means for injecting steam into the path of circulating air entering the lower end of the chimney and into the path of the outside air admitted between the air inlet and the heating coils. n

5. ln a kiln,y the combination of a closed chamber; an air heating Vchimney adjacent the bottom of the kiln open at top and bottoni, the topV opening being smaller than the bottom opening; heating coils in said chimney above the lower end thereof; means for. admitting outside air to the lowerY part of the chimney and an air outletcduct communicating with the interior of the kiln.

6. ln a kiln, the combination of a closed chamber; an air heating chimney adjacent the'bottom of the kiln open at topand bottom; heatin coils in said chimney above the lower end thereof; means for admitting outside air to the lower part of the chimney;

lumber supporting means over the chimney open to permit of the upflow of air from the chimney; and a pile of lumber supported on said means formed with a hollow center over the chimney substantially closed at the top, the pile also being formed with interstices extending laterally from the center to the outside of the pile.

7. In a kiln, the combination of a closed chamber; an air heating chimney adjacent the bottom of the kiln open at top and bottom; heating coils in said chimney above the lower end thereof; means for admitting outside air to the lower part of the chimney; lumber supporting means overY the chimney open to permit of the upow of air from the chimney; and a pile of lumber supported on said means formed with a hollow center over the chimney tapering at opposite sides inwardly from the bottom towards the top, the pile also being formed withfinterstices extending laterally from the center to the outside of the pile. Y

8. In a kiln; the combination of a closed chamber; an air heating chimney adjacent the bottom of the kiln open at top and bottom; means for admitting outside air to the lower part of the chimney; a. steam pipe discharging steam into said chimney; and an air outlet duct communicating with the interior of the kiln.

9. In a kiln; the combinationof a closed chamber; an air heating chimney adjacent the bottom of the kiln open at top and bottom; an inlet for outside air below the lower end of the chimney; and means for injecting steam into the path of circulating air entering the lower end of the chimney and into the path of the outside air admitted between the air inlet and the heating coils.

10. In a kiln, the combination of a closed chamber; an air heating chimney adjacent the bottom of the kiln continuously open at j top andbottom; lids for closing parts of the top opening; heating coils in said chimney above the lower end thereof; means for admitting outside air to the lower part of the chimney; and an air outlet duct communieating with the interior of the kiln.

11. In a kiln, the combination of a closed chamber; an air heating chimney adjacent the bottom of the kiln open at top and bottem; heating coils in said chimney above the lower end thereof; means for admitting outside air to the lower part of the chimney; lumber supporting means over the chimney open to permit of the upflow of air from the chimney; a pile of lumber supported on said means formed with a hollow center over the chimney tapering at opposite sides inwardly from the bottom towards the top, the pile also being formed with interstices extending laterally from the center to the outside of the pile; and means for entirely closing the ends of the hollow center of the pile.

Signed at Toronto, Canada, this 23rd day of May, 1922. ALEXANDER R. DUFF. 

